Never mind, this is what the folder-aware option is supposed to do, but it appears to not be working (unless it is cockpit error again); here is my custom rename string:

[date:yyyy-MM-dd] ###[f,1,3].[ext]{lower}

I don't get a step of 3 and the sequence number does not start over when the folder changes.

Now I can't duplicate it with a small set of pictures; I will have to try again with a larger set.

Changed to minor; I still have a set of pictures I downloaded where it is obvious the sequence number is not getting reset between folders, but the step of 3 is working.

Confirmed that on several folders by date the sequence number does not get reset for each folder, it continues where it left off at the last folder.

I was revisiting this and wondering if folder-aware sequence numbers were based on an INPUT folder designation e.g., if digiKam was working on a set of folders and the sequence number reset happened when the input folder changed (if import can actually work that way in digiKam).

If that is the case, then digiKam probably needs a date-aware modifier where the sequence number changes whenever the photo date changes, like how date-based sub-albums are created.  I guess digiKam would have to keep track of last-sequence-number-per-date for each different date encountered in the import session, in case photos were imported in arbitrary date order.

I'm closing this out because, based on my 2019-02 comment and my discovery of a "Date Folder" option on my most recent camera, it appears that digiKam is performing correctly.  After switching to Date Folders on the camera, digiKam is creating corresponding folders on the host and resetting the sequence numbers in each one, as expected.  In my camera's normal folder mode, the camera would put all pictures, regardless of date, into one folder.  DigiKam would then break these out into date-based folders on the host, but would not reset the sequence number, since the input folder was the same for all photos.  I now realize that folder-aware numbering is associated with input file renaming, whereas date-based folder creation is associated with sub-album creation; I had the two conflated somehow.